Add Linux support

- Add linux build system using MakeGen
- Fix a swapchain validation error, likelydue to my linux system using a
  different vulkan version
- Make DescriptorPool take in amount of descriptors it needs, instead of
  allocating a mass amount for every pool, causing loads of RAM/VRAM usage

CopiumEngine/src/copium/util/FileSystem.cpp

@@ -1,5 +1,10 @@
 #include "copium/util/FileSystem.h"
 
+#include <filesystem>
+#include <fstream>
+#include <sys/stat.h>
+#include <sys/types.h>
+
 namespace Copium
 {
   std::vector<char> FileSystem::ReadFile(const std::string& filename)
@@ -78,4 +83,4 @@ namespace Copium
     CP_ASSERT(stat(filename.c_str(), &result) == 0, "Cannot stat file %s", filename.c_str());
     return (int64_t)result.st_mtime;
   }
-}
+}